The present invention relates to a golf club head, more particularly to the structure of a weight member and a socket therefor.
In golf club heads, a weight member separate from the main body of the club head is often used in order to obtain desired weight distributions to adjust, for example, the gravity point, the sweet spot, the moment of inertia and the like of the golf club head (for example).
In case the of metal wood-type hollow club heads, on the other hand, light-weight, strong metal materials such as titanium alloys have been widely used in recent years. The use of such materials can decrease the wall thickness of the golf club head. Therefore, if a large-sized, heavy weight member can be used in a club head whose wall thickness is relatively thin, then the design freedom will be remarkably increased.
In the laid-open Japanese patent application P2001-276287A, a method of securing a weight member to the main body of the golf club head is disclosed, wherein, as shown in FIGS. 14(a) and 14(b), a cylindrical weight member (c) is positioned in a cylindrical socket (e), with its smaller diameter end portion (c2) protruding from the inner end (e1) of the socket through a smaller diameter opening formed at the inner end (e1) of the socket. The protruding portion (c2) is pressed to deform, expanding over the surface of the inner end (e1) of the socket. In order to facilitate such deformation, the end of the protruding portion (c2) is provided with a hollow (c3).
When the size of the weight member is increased, the pressing force necessary to deform it as indicated above increases at an accelerating pace. Therefore, in this method, near the base of the socket, as indicated by the circles in FIG. 14(b), the wall (a) is subjected to a large stress due to the large compressive stress transferred by the socket as indicated by arrows, which results in unfavorable residual stress or strain or, in the worst case, cracks in the finished article.